Persistent Slabs
- Alpine
- Treeline
- Below treeline
- Likelihood
- Unlikely
- Size
- 1.5–2
Steep slopes above 6,000 feet and shaded areas may still retain the structure for large avalanches capable of burying or injuring a person. The most concerning slopes are those where the top foot or so of snow is cohesive enough to form a slab, and a buried weak layer persists. Upper elevations in the shade, without a surface crust, are the most likely spots to find this problem.
The possible scenario for stumbling across an unlikely spot could be like this:
- You were traveling on a very stout (and miserably difficult) crust when suddenly you transitioned to a colder/shaded slope. The snow beneath feels skiable/rideable. You stop and dig a quick, hasty pit and discover there is 1-2 feet of dense, cold, dry snow that holds together as a cohesive block. Look around and make sure that the terrain you’re entering doesn’t have cliffs, gullies, trees, or other types of hazards below you. Think- IF the terrain you are planning on riding/skiing were to slide, would the runout be clean, or consequential?
A supportable crust underneath you is the safest way to continue enjoying the mountains today.
Consider the consequences IF the unfortunate happens and you are caught in an avalanche. Terrain traps, timber, rocks, or roads could amplify the experience.
The terrain where you find the highest quality of snow right now is unfortunately the most susceptible to a slab over buried weak layer problem.